Food for thought on the defense against infections

This page presents a series of ideas and hypothesis, in short areas for further research.

Colonization resistance details

It is known from previous research that the autochtonous microflora plays a major role in the functioning of
the CR. However, it still is not yet clear which microorganism groups of the indigenous flora are involved, as
well as most biochemical mechanism(s) causing CR. Microbial products such as defensins, short chain fatty
acids, extracellular enzymes, competition for nutrients, etc, all appear to be of importance.

The role of Archaea in the gut ecosystem

Little is known of the existence, let alone the role, of archaea in the gut. For instance which fraction of
what is known now as anaerobic bacteria are actually archaea? Do they play a role in the 'autochtonous
microflora'? Are there any diseases that are actually caused by archaea or their chemical warfare products,
in stead of by bacteria of fungi?

Colonization resistance on the skin

The skin as a habitat for microorganisms differs in many aspects from the gut. Still it is a habitat for
microorganisms and therefor risk of infection is ever present.

Hypothesis: The skin provides a habitat for many microorganisms. These, in
conjunction with other factors help defend the body against (potential) pathogens in a form of
colonization resistance. E.g. the microorganisms that
normally inhabit the skin also help defend it against infections.

Inactivation by binding to " Large Molecular Substances"

Not enough is known about inactivation of defensins and antibiotics by binding to " Large Molecular
Substances". Where do these Large Molecular Substances come from? How do they actually work? How generic
or specific are they?

Hypothesis: Large Molecular Substances are in fact dead microorganisms and parts of microorganisms that have
already fallen apart.
Given that the lifespan of microorganisms in the gut is the hours to days timeframe, a significant percentage
of the microorganisms in the gut will die while located there.

Research by M. Wilkinson shows ....

Anaerobic microorganisms also play a significant role in the colonization resistance

Are (anaerobic)microorganisms that do not translocate but are (semi)persistent also part of the colonization
resistance? ==> MORE TO BE DONE

There is a significant increase in defensin production in the child's gut shortly after birth

It is unknown if there is an increase in defensin production in the child's gut shortly after birth. Such an
increase would make sense as the digestive tract is not colonized by any microorganism at birth and therefore
provides ample opportunities for excessive growth. In a fully colonized digestive tract the microorganisms
that live in it also produce defensins and compete for food and space. This has not yet developed in the
early days after birth.
If a potential pathogen microorganism is an early colonizer, this may lead to significant invasion of the
newborn child. As its adaptive immune system is still almost unformed this could easily have dire
consequences. So some extra activity from the innate defense system would be likely.